When people suffer from some types of heart arrhythmia, the result may be that blood flow to various parts of the body is reduced. Some arrhythmias may even result in a Sudden Cardiac Arrest (SCA). SCA leads to death very quickly, e.g. within 10 minutes, unless treated in the interim.
People who have had a heart attack have an increased risk of SCA, and therefore it is recommended that they receive an Implantable Cardioverter Defibrillator (“ICD”). An ICD has internal electrodes, and continuously monitors the person's electrocardiogram (“ECG”). If certain types of heart arrhythmia are detected, then the ICD delivers an electric shock through the heart.
People with increased risk of an SCA are sometimes given a wearable external defibrillator system. The recipients typically include those who have had a heart attack, or SCA, or are considered at risk, but have not yet had an ICD implanted. A wearable defibrillator system typically includes a harness, vest, or other garment for wearing by the patient. The system includes a defibrillator and external electrodes, which are attached on the inside of the harness, vest, or other garment. When the patient wears the system, the external electrodes may then make good electrical contact with the person's skin, and therefore can help monitor the patient's ECG. If a shockable heart arrhythmia is detected, then the defibrillator delivers the appropriate electric shock through the body, and thus through the heart.